POS1005 ACTIVE INFLAMMATORY LESIONS OF THE SPINE IN SACROILIAC JOINTS MRI (SIJs-MRI): AN OVERLOOKED FINDING BY RADIOLOGISTS.
Authors: N. Di Meglio, F. Gentili, S. Guerrini, G. Bagnacci, A. Perrella, E. Conticini, B. Frediani, L. Cantarini, L. Volterrani, M. A. Mazzei
Journal: Annals of the Rheumatic Diseases (2022)

Background Establishing a diagnosis for axial spondylarthritis (axSpA) is based on the combined presence of several clinical and laboratory features in association with imaging: the presence of active inflammatory lesions (bone marrow edema, BME) in sacroiliac joints (SIJs), also associated with structural lesions, is the main element in favor of a diagnosis of axSpA and SIJ MRI is currently the main recommended technique for detecting inflammation, enabling early diagnosis in patients with normal radiographic findings. MRI of the spine is generally not recommended for axSpA diagnosis, since spine involvement is considered less sensitive and specific. Several studies explored the incremental value of spine MRI for diagnosing patients with axSpA, especially when the findings of SI are equivocal, and “predicting” clinical disease activity. Objectives To evaluate the effectiveness of the MRI study dedicated to SIJs to identify the inflammatory involvement of the lumbar spine in patients with active sacroiliitis and clinical diagnosis of axSpA. Methods MRI of 96 patients (26 M, 70 F, mean age 48 years) with SIJs-MRI positive for inflammatory involvement according to ASAS criteria, were evaluated retrospectively. The presence of signs of inflammation of posterior spinal elements and vertebral bodies included in the field of vision (FOV) was therefore researched Results Of 96 patients with active sacroiliitis, 88 had concomitant inflammatory lesions of the lumbar spine. Facet capsulitis (87.6 %) and posterior enthesitis (42.2 %) were the most common lesions and these lesions frequently coexisted (39.3%). Twelve patients with facet capsulitis presented also facet arthritis. Only 20 out of 96 patients (22%) had vertebral bodies inflammatory lesions: 15 corner inflammatory lesions and 5 aseptical spondylodiscitis. Conclusion On the basis of current working consensus MRI examination of the spine is not recommended for axSpA diagnosis, because it is considered less sensitive and specific. However the high prevalence (91.7%) of spinal inflammatory changes in patients with active sacroiliitis suggests that these features can be used as an additional element in favor of diagnosis, especially in doubtful cases. This evaluation takes little reporting time, without any increase in MRI execution time. References [1]Lambert RG, Bakker PA, van der Heijde D, Weber U, Rudwaleit M, Hermann KG, Sieper J, Baraliakos X, Bennett A, Braun J, Burgos-Vargas R, Dougados M, Pedersen SJ, Jurik AG, Maksymowych WP, Marzo-Ortega H, Østergaard M, Poddubnyy D, Reijnierse M, van den Bosch F, van der Horst-Bruinsma I, Landewé R. Defining active sacroiliitis on MRI for classification of axial spondyloarthritis: update by the ASAS MRI working group. Ann Rheum Dis. 2016 Nov;75(11):1958-1963. doi: 10.1136/annrheumdis-2015-208642. [2]Maksymowych WP, et al. MRI lesions in the sacroiliac joints of patients with spondyloarthritis: an update of definitions and validation by the ASAS MRI working group. Ann Rheum Dis. 2019 Nov;78(11):1550-1558. doi: 10.1136/annrheumdis-2019-215589. [3]Hermann KG, et al. Assessment in SpondyloArthritis international Society (ASAS). Descriptions of spinal MRI lesions and definition of a positive MRI of the spine in axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI study group. Ann Rheum Dis. 2012 Aug;71(8):1278-88. doi: 10.1136/ard.2011.150680. [4]van der Heijde D, et al. Spinal inflammation in the absence of sacroiliac joint inflammation on magnetic resonance imaging in patients with active nonradiographic axial spondyloarthritis. Arthritis Rheumatol. 2014 Mar;66(3):667-73. doi: 10.1002/art.38283. [5]Bennett AN, et al. Evaluation of the diagnostic utility of spinal magnetic resonance imaging in axial spondylarthritis. Arthritis Rheum. 2009 May;60(5):1331-41. doi: 10.1002/art.24493. Erratum in: Arthritis Rheum. 2010 Oct;62(10):3005. PMID: 19404934.D Figure 1. Disclosure of Interests None declared